Channel state information (CSI) fed back by a terminal to a network device is a generic term for various types of indication information. For example, the indication information may be channel quality indicator (CQI), precoding matrix indicator (PMI), rank indication (RI), layer indicator (LI), or CSI-reference signal resource indicator (CRI). The CSI reported by the terminal may include one or more types of indication information. Quantity of types of indication information included in the CSI may vary each time, and payload length of the CSI reported by the terminal also varies. The payload length of the CSI may also be referred to as a length of the CSI. The CSI reported by the terminal may be of different reporting types, for example, different ranks, different codebook type configurations, or different quantities of CSI-reference signal (CSI-RS) ports. A length of each type of indication information varies with the reporting type. Therefore, even if the CSI reported by the terminal every time includes a same quantity of types of indication information, lengths of the entire CSI are different.
After receiving the CSI from the terminal, the network device decodes the CSI. If the payload length of the CSI cannot be determined, the network device needs to perform blind detection multiple times. Consequently, decoding efficiency is low, and decoding resource is wasted.